Highly integrated electronic component with heat-conducting plate

ABSTRACT

A highly integrated electronic component comprised of a semiconductor body cast into a plastics enclosure. A multiplicity of metallic terminals protrude from the plastic enclosure, and a heat-conducting plate is cast into the plastic enclosure and is in surface contact with an underside of the semiconductor body. Good heat removal and an increase in the mechanical stability for the terminals are achieved by the heat-conducting plate being substantially planar and bearing both against the underside of the semiconductor body and against the underside of the terminals and by the upper side of the heat-conducting plate having a thin, electrically insulating layer.

BACKGROUND OF THE INVENTION

The invention relates to a highly integrated electronic componentcomprising a semiconductor body cast into a plastic enclosure, amultiplicity of metallic terminals which protrude from the plasticenclosure, and a heat-conducting plate. The plate is cast into theplastic enclosure and is in surface contact with an underside of thesemiconductor body.

The fabrication of highly integrated electronic components is leading toan ever greater integration density, that is to say to an ever greaternumber of electronic components realized on a plastic body. With theincrease in components, the number of terminals leading out from thesemiconductor body increases. Presently terminal numbers in excess of200 are already possible. The terminals are usually produced with leadframes, generally with leads which are cut out from a sheetlikematerial. The connection of the terminals to the corresponding terminalfaces of the semiconductor body is generally established with the aid ofbonding wires. After separating the frame connecting the free ends ofthe terminal conductors, the terminals are regularly bent off through90°. This facilitates the automatic soldering into a circuit board orthe like. The mechanical stability of the component is established bythe plastic enclosure. With the increasing number of electroniccomponents integrated in the plastic body, the energy consumed in thesemiconductor body increases. It is therefore known to bring thefinished highly integrated electronic component into contact withheat-conducting plates. The heat removal thereby achieved is of coursesmall.

It is further known to provide a component comprising a semiconductorbody and a plastic enclosure with an integrated heat-conducting plate.The heat-conducting plate is shaped in such a way that the underside ofthe semiconductor body is in contact with the heat-conducting plate. Theterminals extend upwards at an angle from the semiconductor body andthen run horizontally to the outside of the plastic enclosure. Theheat-conducting plate is bent off obliquely downward from the undersideof the semiconductor body so as to run at a certain distance parallel tothe terminals horizontally in the plastic enclosure. This shapingensures that no electric contact takes place between the terminals andthe heat-conducting plate.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved highly integrated electronic component of the type previouslydescribed.

A further object of the invention resides in the provision of animproved highly integrated electronic component that has improvedperformance properties and can be fabricated more easily.

In accomplishing the foregoing objects, there has been provided anelectronic component comprising a semiconductor body cast into a plasticenclosure, multiple metallic terminals which protrude from the plasticenclosure, and a heat-conducting plate which is cast into the plasticenclosure and is in surface contact with an underside of thesemiconductor body, wherein the heat-conducting plate is substantiallyplanar and bears both against the underside of the semiconductor bodyand against the underside of the terminals and wherein the upper side ofthe heat conducting plate contains an electrically insulating layer.

Further objects, features and advantages of the present invention willbecome apparent from the detailed description of preferred embodimentsthat follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross section through a first embodiment of a highlyintegrated electronic component,

FIG. 2 shows a plan view of the component according to FIG. 1 withdrawn-in heat-conducting plate and partially removed plastic enclosure,

FIG. 3 shows a plan view according to FIG. 2 with a larger semiconductorbody,

FIG. 4 shows a cross section through a second embodiment of a highlyintegrated electronic component, and

FIG. 5 shows a plan view of the heat-conducting plate used in the caseof the component according to FIG. 4.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention is therefore based on the problem of designing theheat-conducting plate in such a way that the heat-conducting plate notonly provides good heat removal but also provides support for themechanical stability of the terminals. To solve this problem, theheat-conducting plate is provided on its upper side with a thin,electrically insulating layer, preferably, which should not markedlyimpair the thermal conductivity.

Such an electrically insulating layer which does not markedly impair thethermal conductivity can be formed in a preferred embodiment byanodizing the heat-conducting plate. In this case, the anodizing shouldhave a minimum thickness of about 30 μ. Other insulating layers are alsosuitable.

The fabrication of the highly integrated electronic component issimplified if the heat-conducting plate is provided with embossed feet,by which it can be placed into the injection mold for the plasticenclosure. Consequently, on the finished component the embossed feetextend to the underside of the plastic enclosure.

For satisfactory production of the plastic enclosure it has provedbeneficial, especially in the case of a rectangular highly integratedelectronic component, for the heat-conducting plate to be shaped in sucha way that said plate has a substantially rectangular outer contourcoinciding with the rectangular shape of the plastic enclosure.Preferably the plate is provided in the corners with diagonally runningincisions. These incisions preferably extend almost up to thesemiconductor body, while maintaining adequate stability of theheat-conducting plate. The diagonal incisions provide good, uniformplastic transport during the injection-molding of the plastic for theplastic enclosure through the planes of the heat-conducting plate, sothat a void-free, undisturbed plastic enclosure can be produced on bothsides. In an additional form of shaping, it has been found to bebeneficial if, at two diagonally opposite corners, the heat-conductingplate is extended up to the side edges of the plastic enclosure by twowebs bounding the diagonal incisions, whereas at the two other cornersthe plate maintains a distance from the side edges of the plasticenclosure.

For sizeable components, which consequently also require a sizeableheat-conducting plate, the moldability of the plastic enclosure isfacilitated if through-openings in the heat-conducting plate arearranged around the semiconductor body. These through-openings arepreferably of an elongate design and radially extended.

With the heat-conducting plates according to the invention, previouslyunachievable degrees of integration of the highly integrated electroniccomponents can be realized in plastic packages. The heat which isgenerated by the component is reliably removed, and the stability of theterminal arrangements is significantly increased by the heat-conductingplate. In addition, the planar design of the heat-conducting plateallows the use of various chip sizes without changing the configurationof the heat-conducting plate.

The invention is to be explained in greater detail below with referenceto the illustrative embodiments represented in the drawings.

The highly integrated electronic component represented in FIGS. 1 and 2has an approximately square base shape and comprises a semiconductorbody 1, the terminal faces of which are connected by bonding wires 2 toterminals 3 .The terminals extend in the component initially with ahorizontal section 4 up to the side edges of a plastic enclosure 5 andoutside the plastic enclosure 5 have bent-off ends 6.

The semiconductor body 1 rests with its underside in surface contactwith a heat-conducting plate 7, which plate is substantially planar andsupports the horizontal sections 4 of the terminals 3.

The heat-conducting plate optionally is provided with four embossed feet8, which extend as far as the underside of the plastic enclosure 5.

FIG. 2 illustrates the contour of the heat-conducting plate 7, thecontour substantially corresponding to the outer contour of thecomponent. However, in the region of the corners the heat-conductingplate is provided with diagonally running incisions 9, which arelaterally bounded in each case by two webs 10, which extend virtually upto the side edges of the plastic enclosure 5.

FIG. 2 indicates that four feet 8 are provided, each of which isarranged close to the edge of the heat-conducting plate 7 and centrallybetween the diagonally running incisions 9. In order to ensure a largepassage cross section for the plastic during the injection molding ofthe plastic enclosure 5, the incisions 9 extend almost up to thesemiconductor body 1. There are further provided between the diagonallyrunning incisions 9 in each case two through-openings 11, which are ofan elongate design and are approximately radially aligned. The eightthrough-openings 11 are distributed approximately evenly around thesemiconductor body 1. The through-openings further ensure a largepassage cross-section for the plastic during the injection molding ofthe plastic enclosure.

FIG. 2 further reveals that the heat-conducting plate 7 supports theterminals 3 and is in contact with them. Since the heat-conducting plateregularly consists of electrically conducting material, the plate mustbe of an electrically insulated design on the upper side, which comesinto contact with the terminals 3. For this purpose, the heat-conductingplate 7 according to the invention has a thin insulating layer on theupper side, which is preferably formed by anodizing with a minimumthickness of about 30 μ.

FIG. 3 illustrates that the heat-conducting plate 7 of FIGS. 1 and 2 canalso be used with a significantly larger semiconductor body 1'. Hence, aplate can be used with different sizes of semiconductor bodies.

In FIGS. 4 and 5, a further embodiment is represented, in which theparts corresponding to the embodiment according to FIGS. 1 and 2 areprovided with identical reference numerals, but indicated by a "'".

FIG. 4 has only minor differences from the representation of FIG. 1.Specifically, FIG. 5 illustrates that the component is not of a squarebut of a rectangular design, with two long sides and two short sides.The feet 8' are arranged next to each other on the long sides of theheat-conducting plates 7'. The diagonal incisions 9' are bounded only attwo diagonally opposite corners by the webs 10'. The webs extend up tothe side edges of the - plastic enclosure 5', whereas at the two othercorners these webs 10' are missing. The heat-conducting plate 7' is notprovided with further through-openings because its smaller size allowsan adequate flow of the plastic from one side of the heat-conductingplate 7' to the other through the incisions 9'.

The diagonal incisions 9, 9', which start from the corners of theheat-conducting plate 7, 7', represent the best arrangement to ensure ahigh passage of material with as little weakening as possible of thesupporting base for the terminals 3.

The heat-conducting plates 7, 7' represented therefore allowtrouble-free injection-molding of the plastic enclosure 5, 5', goodremoval of the heat produced in the semiconductor body 1 as well as goodmechanical support of the thin terminals 3 in the region of thehorizontal sections 4.

What is claimed is:
 1. An electronic component comprising asemiconductor body cast into a plastic enclosure, multiple metallicterminals which for a substantial part of their lengths extend withinthe plastic enclosure and protrude with distal ends from the plasticenclosure and a heat-conducting plate which is cast into the plasticenclosure and is in surface contact with an underside of thesemiconductor body, wherein the heat-conducting plate is substantiallyplanar and bears against the underside of the semiconductor body andagainst the underside of the terminals essentially along the completeextension of the terminals within the enclosure so as to establish aplanar support of the terminals, and wherein an upper side of theheat-conducting plate contains an electrically insulating layer, andwherein the heat-conducting plate contains through-openings arrangedaround the semiconductor body, and wherein the through-openings are ofan elongate design and radially extended from the semiconductor body. 2.The electronic component as claimed in claim 1, wherein said insulatinglayer is formed by anodizing the heat-conducting plate.
 3. Theelectronic component as claimed in claim 2, wherein said insulatinglayer formed by said anodizing has a minimum thickness of about 30 μ. 4.The electronic component as claimed in claim 1, wherein thethrough-openings are arranged in approximately even distribution aroundthe semiconductor body.
 5. The electronic component as claimed in claim1, wherein said heat-conducting plate is not adhesively bonded to eitherof said semiconductor body and said terminals.
 6. An electroniccomponent comprising a semiconductor body cast into a plastic enclosure,multiple metallic terminals which for a substantial part of theirlengths extend within the plastic enclosure and protrude with distalends from the plastic enclosure and a heat-conducting plate which iscast into the plastic enclosure and is in surface contact with anunderside of the semiconductor body, wherein the heat-conducting plateis substantially planar and bears against the underside of thesemiconductor body and against the underside of the terminalsessentially along the complete extension of the terminals within theenclosure so as to establish a planar support of the terminals, andwherein an upper side of the heat-conducting plate contains anelectrically insulating layer, and wherein the heat-conducting plate isprovided with embossed feet which extend to the underside of the plasticenclosure.
 7. The electronic component as claimed in claim 6, whereinsaid heat-conducting plate is not adhesively bonded to either of saidsemiconductor body and said terminals.
 8. The electronic component asclaimed in claim 6, wherein said insulating layer is formed by anodizingthe heat-conducting plate.
 9. The electronic component as claimed inclaim 8, wherein said insulating layer formed by said anodizing has aminimum thickness of about 30 μ.
 10. An electronic component comprisinga semiconductor body cast into a plastic enclosure, multiple metallicterminals which for a substantial part of their lengths extend withinthe plastic enclosure and protrude with distal ends from the plasticenclosure and a heat-conducting plate which is cast into the plasticenclosure and is in surface contact with an underside of thesemiconductor body, wherein the heat-conducting plate is substantiallyplanar and bears against the underside of the semiconductor body andagainst the underside of the terminals essentially along the completeextension of the terminals within the enclosure so as to establish aplanar support of the terminals, and wherein an upper side of theheat-conducting plate contains an electrically insulating layer, andwherein the heat-conducting plate has a rectangular outer contoursubstantially coinciding with a rectangular shape of the plasticenclosure, wherein said plate is provided in each corner with diagonallyrunning incisions.
 11. The electronic component as claimed in claim 10,wherein the heat-conducting plate is extended up to side edges of theplastic enclosure by two webs bounding at least one of said incisions.12. The electronic component as claimed in claim 11, wherein the websare present at two diagonally opposite corners, wherein at the two othercorners the webs are missing.
 13. The electronic component as claimed inclaim 10, wherein said insulating layer is formed by anodizing theheat-conducting plate.
 14. The electronic component as claimed in claim13, wherein said insulating layer formed by said anodizing has a minimumthickness of about 30 μ.
 15. The electronic component as claimed inclaim 10, wherein said heat-conducting plate is not adhesively bonded toeither of said semiconductor body and said terminals.